1. Field of the Invention
The present invention generally relates to an image display apparatus capable of simultaneously displaying plural images on the same screen. More specifically, the present invention is directed to a so-called multi-frame type display apparatus and also to an ultrasonic diagnostic apparatus capable of representing a plurality of ultrasonic images in a multi-frame mode.
2. Description of the Related Art
A so-called "multi-frame" type ultrasonic diagnostic apparatus is known in the art, for instance, from U.S. Pat. No. 4,398,540 issued on Aug. 16, 1983 to Takemura et. al. entitled "COMPOUND MODE ULTRASOUND DIAGNOSIS APPARATUS". In this conventional ultrasound diagnosis apparatus, for example, both the B-mode image and M-mode image are concurrently displayed on the same TV screen.
In another conventional multi-frame type ultrasonic diagnostic apparatus, more than two, e.g., four ultrasonic images are simultaneously displayed on the same TV screen. That is, the entire TV screen is subdivided into four screen regions. A first selection is made to a plurality of ultrasonic images which have been stored in the buffer memory. In this case, since the selected ultrasonic images are successively displayed on the first subdivided screen region, an operator must successively watch the ultrasonic images displayed on the small (subdivided) screen region. When the first selection is completed, the first-selected ultrasonic image is temporarily stored in the buffer memory and then read out therefrom for the display purpose with 1/4-reduced screen size. Thereafter, a second selection is similarly commenced. Thus, the second-selected ultrasonic image is also temporarily stored in this buffer memory and then displayed with another 1/4-reduced screen size. After the fourth selection has been accomplished, all these selected ultrasonic images are being simultaneously displayed on the same TV screen with 1/4-reduced sizes.
In the above-described conventional multi-frame type image display apparatus, there are the following drawbacks. That is to say, first, the cumbersome image selecting operation is necessarily required in accordance with an increase of the selecting image quantity. Secondly, since such an image selection must be carried out on the small-sized TV screen region, the resolution of one image displayed on such a small-sized TV screen region is not so good as compared with that displayed on the full-sized screen.
As a result, a lengthy selecting operation and a heavy workload are required so as to achieve such a multi-frame image represention. Moreover, the diagnostic capabilities cannot be improved, because the resolution of the multi-frame mode images is not so high.
The present invention has been made in an attempt to solve the above-described drawbacks of the conventional multi-frame type image display apparatus, and therefore has an object to provide a multi-frame type image displaying apparatus and also an ultrasonic diagnostic apparatus utilizing such a multi-frame image display mode, capable of realizing an easy and simple image selecting operation, and also higher resolution of selected images.